Tom Coburn is leaving the Senate early with a proposal to save private insurance from the ravages of ObamaCare.

Tom Coburn stood for Congress in 1994 as a political tenderfoot for two main reasons: As an obstetrician he thought government was impinging too much on his medical practice, and the nine-term House Democrat who held his Oklahoma district's seat favored the Clinton national health plan then under consideration. Another reason Dr. Coburn entered the race, he says, was that "the cowardice of career politicians...